Vapor generating and superheating apparatus



Oct. 11, 1966 E. A. BLUM ETAL 3,277,871

VAPOR GENERATING AND SUPERHEATING APPARATUS Filed Oct. 2, 1964 5Sheets-Sheet l INVENTORS Erdman A. Blum Alberr O. Downs,Jg'. Mlchael.Sanfuccl 5 Sheets-Sheet 2 pm I 3 I v. i I 1 T r FIG-4 FIG.5

E. A. BLUM ETAL VAPOR GENERATING AND SUPERHEATING APPARATUS Oct. 11,1966 Filed Oct. 2, 1964 aim.

Oct. 11, 1966 A. BLUM ETAL VAPOR GENERATING AND SUPERHEATING APPARATUSFiled Oct. 2, 1964 5 Sheets-Sheet 5 FIG.7

4 I O O O:

United States Patent 3,277,871 VAPOR GENERATING AND SUPERHEATINGAPPARATUS Erdman A. Blunt and Albert 0. Downs, .lr., Akron, and MichaelC. Santncci, Barberton, Ohio, assignors to The Babcock ll; WilcoxCompany, New York, N.Y., a corporation of New Jersey Filed Oct. 2, 1964,Ser. No. 401,192 3 Claims. (Cl. 12251tl) This invention relatesgenerally to vapor generating and .superheating apparatus, especially tothose of the kind having a furnace chamber provided with a roof throughwhich fluid heating tubes extend, terminating in an adjacent compartmentor chamber. More particularly, the invention relates to an improvedinsulating roof construction of the type set forth which minimizesleakage of fly ash through the clearance space between the tubes and theedges of the holes in the roof.

The wall structure of conventional vapor generating and superheatingunits encloses not only a lower furnace chamber, but also an upperchamber or so-called penthouse which is partitioned from the furnacechamber by a horizontally extending furnace roof of refractoryconstruction. As is well known, upright fluid heating tubes extend fromthe furnace chamber through the furnace roof into the penthouse, wherethey are rigidly connected to horizontally elongated headers. Whenheated, the tubes undergo thermal expansion in a downward direction fromthe point of restraint at the header. Also, horizontal thermal expansionof the header tends to increase the horizontal spacing of the tubes,thus producing a sidewise movement of the tubes which can break up thesurrounding refractory and make a path for the leakage of fly ash fromthe furnace chamber into the penthouse.

One of the objects of the present invention is to provide a refractoryroof construction which permits unrestrained longitudinal movement ofthe upright tubes relative to the roof as a result of thermal expansion;which minimizes leakage of fly ash through the clearance space betweenthe tubes and the roof material surrounding the tubes; and whichprovides restraint against sidewise motion of the tubes caused bythermal expansion of the header in order to maintain the small clearancespace between the tubes and the roof material.

According to the present invention, the insulating roof is of multilayerconstruction, the intermediate layer being mineral wool and preferably aresilient mass of refractory monofilaments. The resilient wool layersurrounds the upright tubes extending therethrough, and comes intoengagement with one or more collars secured in sealing relationship tothe outer surface of each tube to establish a seal therewith. It is thefunction of the resilient wool layer, not only to provide insulatingcharacteristics to the roof, but also to cooperate with the collars onthe tubes in resisting the flow of fly ash along the tubes in thedirection of the penthouse. It is a feature of this labyrinth and filterconstruction that unrestrained longitudinal expansion of the tubesrelative to the roof is permitted because the compressible mass ofinsulating wool yieldingly resists the longitudinal movement of thecollars.

In one form of the present invention, the resilient layer of wool-likerefractory material is disposed between two rigid layers of castablerefractory material. The castable refractory material has insulatingproperties; but, because of its brittleness, means are provided toprevent the upright tubes from moving sidewise and breaking the edges ofthe refractory as the header undergoes horizontal thermal expansion.According to the present invention, there is provided for each row oftubes a bar or brace having snugly fitting holes for the respectivetubes, the holes being sized and positioned to permit relative slid-3,277,871 Patented Oct. 11, 1966 ing movement of the tubes whilemaintaining a sealing relationship therewith. By securing the brace, asby welding, to the metal frame surrounding the roof, the tubes areprevented from moving laterally in any horizontal direction.

Another way of preventing lateral movement of the upright tubes is toinstall bars which fit snugly between neighboring rows of tubes, andsecuring the bars at their ends to the metal frame. The spaces betweenthe bars and the tubes can be sealed at the top surface of the roof bymeans of plates having holes for snugly receiving the tubes, with theplates welded to the bars.

Drilled plates can be employed to prevent lateral movement of the tubesalong the length of the tube row, and spacer bars between the tube rowscan be employed to prevent lateral movement of the tubes at right anglesto the longitudinal extent of the tube row. The bars and plates may alsobe disposed in the layer of mineral wool, beneath a sealing layer ofcastable refactory material.

Various other objects, features, and advantages of the invention willappear more fully from the detailed description which follows, taken inconnection with the accompanying drawings forming a part of the presentapplication, and in which:

FIG. 1 is a sectional elevational view of a forced-circulation,once-through vapor generating and superheating unit to which theinvention has been applied,

FIG. 2 is a view, partly in section and partly in elevation, takenvertically through the roof of the unit of FIG. 1, showing one form ofroof seal of the present invention in detail,

FIG. 3 is a horizontal sectional view, taken along line 33 of FIG. 2,

FIG. 4 is a view similar to FIG. 2, showing a modified form of theinvention,

FIG. 5 is a horizontal sectional view, taken 55 of FIG. 4,

FIG. 6 is another view similar to FIG. 2, showing the invention in stillanother modified form, and

FIG. 7 is a horizontal sectional view, taken along line 7-7 of FIG. 6.

In the drawings, the invention has been applied to a top-supported,forced-flow, once-through vapor generating and superheating unitdesigned for the production of su erheated steam.

The illustrated unit includes wall structure defining a shell 10 with afurnace chamber 12 in the lower portion of the shell and a penthouse 14in the upper portion of the shell. The furnace chamber 12 and thepenthouse 14 are separated by a horizontally extending, insulatingpartition serving as the roof 16 of the furnace chamber. The furnacechamber 12 may have a gas outlet 18 at its upper end, opening to ahorizontally extending gas pass 20 which, in turn, communicates at itsrear end with the upper end of an upright gas passage 22. At the lowerportion of the furnace chamber 12 is a fuel firing section consisting ofhorizontally extending cyclone type furnaces 24 which serve to burn fueland to discharge high temperature gaseous products of combustion intothe lower portion of the furnace chamber 12, while discharging separatedash residue and molten slag.

The gas pass 20 is occupied by a first stage secondary superheater 26, areheater 28, and a second stage secondary superheater 30, arranged inseries with respect to gas flow. The gas passage 22 is occupied by aprimary superheater 32 and an economizer 34, also arranged in serieswith respect to gas flow.

The vapor generating and superheating unit may be top-supported bystructural steel members from which the wall structure defining shell 10is supported. The upper portions of the upright tubes 36 of thesecondary superheaters 26 and 30 pass through the roof 16 for securementalong line to the headers 38 and 40, and they are expansibly secured tothe roof in sealing relation therewith to permit differential movementaccording to the present invention, as described hereinafter in detail.

Referring now to FIGS. 2 and 3 of the drawing, there is shown,immediately above the horizontal roof tubes 42, a box-like steel frame44 which is open at the top to receive roof insulating material. Theframe 44 comprises four angle irons 46 extending about the periphery ofthe frame 44 to close the sides thereof. The bottom of the frame 44 isclosed by a plate 48 apertured to receive the upright superheater tubes36 in a closely fitting relationship which permits differential movementof the tubes 36 in vertical direction.

The refractory roof 16 of FIGS. 2 and 3 comprises three layers ofinsulating material. The lower layer 54 is a eastable refractorymaterial which is poured into the frame 44 in plastic condition and setsto form a hard, rigid mass. If poured with stilf consistency, the bottomplate 48 can be eliminated from the frame 44, and the material may bepoured directly on top of the roof tubes 42 and the reinforcing wiremesh (not shown). The intermediate or second layer 56 is a resilientbody of mineral wool comprising a loosely packed, noncrystalline,fibrous mass which may be made as monofilaments from molten Georgiakaolin or other refractory material according to the disclosure in US.Patent No. 2,467,889, issued April 19, 1949, in the names of IsaacHarter, Charles L. Norton, Jr., and Leonard D. Christie, Jr., andassigned to The Babcock & Wilcox Company. The third or upper layer 58 issimilar to the lower layer 54, and it may be poured directly on top ofthe mineral wool layer 56. Thus, the mineral wool layer 56 is sandwichedbetween the two layers 54 and 58 of rigid eastable refractory material.

Still referring to FIGS. 2 and 3, the upright tubes 36 are each providedwith at least one annular member or collar 60 secured in sealingrelationship thereto, as by welding the inner edge of the collar to theouter surface of the tube 36. The collars 60 can be installed before thetubes 36 are in position and connected to the headers, or the collars 60may be made in two or more parts and later joined together and securedto their respective tubes 36. The collars 60 are preferably positionedin vertically staggered and horizontally overlapping relationship, asshown, when neighboring tubes 36 are closely spaced and the collarswould otherwise interfere with each other.

According to the invention, the collars 60 are disposed in an upperportion of the refractory wool layer 56 which yields to the downwardmovement of the collars as the tubes 36 undergo thermal expansion, thusmaintaining the sealing relationship with the collars 60 withoutforcibly resisting their downward movement, and thereby preventing thedevelopment of bending and compressive stresses in the tubes. Theforegoing arrangement of FIGS. 2 and 3 permits differential movement ofthe tubes 36 relative to the roof 16 and, at the same time, provides alabyrinth and filter construction which minimizes the leakage of fly ashfrom the furnace chamber 12 to the penthouse 14.

A modified form of the invention is shown in FIGS 4 and 5, wherein likereference numerals are employed to designate parts which correspond tosimilar parts in the embodiment of FIGS. 2 and 3. In this embodiment ofthe invention there is a lower layer 54 of eastable refractory material,and an intermediate blanket or layer 56 of refractory wool materialdisposed in engagement with the collars 60 on the upright tubes 36.Instead of an upper layer 58 of refractory material, however, the roof16 is sealed at the upper surface thereof by means of tube spacermembers 62 and tube tie bars 64, both of which extend horizontally. Thespacer members 62 are of heavy gauge metal with a rectangular crosssection; and they fit snugly between neighboring upright tube rows tothereby maintain their spacing and secure them against movement in onehorizontal direction. The spacer members 62 may be installed by layingthem horizontally on top of the wool layer 56 to compress the loose wooland pack it around the tubes 36, after which the ends of the spacermembers 62 may be secured to the frame 44, as by welding.

There is a tie bar 64 for each tube row extending horizontally along theseries of tubes 36 in the row and having holes for slidably receivingthe respective tubes 36. The tie bars 64 are lowered until they come torest on the spacer members 62. Preferably, the long sides of each tiebar 64 are welded to the upper surfaces of subjacent spacer members 62and the end portions thereof are Welded to the metal frame 44. Thisarrangement provides another roof seal which minimizes the leakage offly ash into the penthouse 14, and yet permits longitudinal movement ofthe superheater tubes 36 relative thereto.

In the arrangement of FIGS. 2 and 3, the tie bars 64 hold the tubes 36against horizontal movement relative to one another longitudinally ofthe tube row; whereas the spacer members 62 secure the tubes 36 againstmovement in a horizontal direction at right angles to the longitudinalextent of the tube row. By preventing transverse or sidewise movement ofthe tubes 36, such as during horizontal thermal expansion of the headers38 and 40, the brittle refractory material in the lower layer 54 isprotected against breakage around the hole edges, with the result thatthe clearance space between the tubes 36 and the refractory roof 16 ismaintained and leakage of fly ash is minimized.

Still another form of the invention is shown in FIGS. 6 and 7, whereinlike reference numerals are again employed to designate parts whichcorrespond to similar parts of the previously described embodiments ofthe invention. An intermediate layer 56 of refractory wool material isdisposed between upper and lower layers 58 and 54 of eastable refractorymaterial. The upright tubes 36 are provided with collars 60 disposed inthe lower layer 54 of eastable refractory material, quite unlike theprevious embodiments wherein the collars 60 are disposed in theresilient intermediate layer 56. In order to provide the clearance whichpermits differential longitudinal movement of the upright tubes 36, thetubes 36 may be moved up and down forcibly as the eastable material issetting, or heat may be alternately applied and removed to alternatelyelongate and shorten the tubes 36 while the lower layer 54 is in plasticcondition, with the result that the collars 60 moving therewithestablish for themselves voids 66 which provide the requisite verticalclearances in the lower layer 54. The same clearances prevail after thelower layer 54 has set into a rigid mass, and the differential movementof the tubes 36 and the collars 60 takes place without appreciableopposition during operation of the apparatus.

In the roof construction of FIGS. 6 and 7, tie bars 64 hold the tubes 36in row against transverse movement along the length of the tube row, andspacer members 62 between tube rows hold the tubes 36 against transversemovement at right angles to the longitudinal extent of the tube row. Thespacer members 62 and the tie bars 64 may be rested on the resilientwool layer 56 so as to compress the wool layer 56 with weight. Next, theupper layer 58 of eastable refractory material may be poured over thespacer members 62 and tie bars 64 to seal the roof 16. The tie bars 64in the intermediate layer 56 assist the collars 60 in the lower layer 54in preventing fiy ash from flowing along the length of the tubes 36; thetie bars 64 secure the tubes 36 in a tube row against horizontalmovement in one direction; and yet the tubes 36 are free to movevertically relative to the roof 16.

Although the invention has been shown in but several forms, it will beobvious to those skilled in the art that it is not so limited, but it issusceptible of various changes and modifications without departing fromthe spirit thereof as set forth in the following claims.

What is claimed is:

1. In vapor generating and superheating apparatus, the

combination of wall structure defining a shell having upper and lowercompartments and including an internal horizontal partition between saidupper and lower compartments,

said lower compartment including a furnace chamber,

a plurality of superheater headers disposed in said upper compartment,

a plurality of rows of upright tubes, each extending through saidpartition into said upper compartment and connected to at least one ofsaid headers,

said partition including:

a plurality of horizontally extending, fluid-conducting tubes arrangedclosely spaced in a row at the bottom of said partition,

a plurality of horizontally extending, elongated metal members joined toone another along adjacent longitudinal edge portions to form afluidtight top surface of said partition, with at least some of theelongated members having a longitudinal series of holes slidablyreceiving respective upright tubes to hold said tubes in row and againsttransverse movement,

and a body of insulating refractory material between said horizontaltubes and the top of said partition including a layer of castablerefractory material poured in place so as to rest upon said horizontaltubes and be supported thereby.

2. In apparatus according to claim 1, the combination as set forthwherein the body of insulating material in said partition furtherincludes a compressible layer of resilient wool material above saidlayer of castable material, and including an annularly disposed collaron each of said upright tubes engaging said compressible layer.

3. In apparatus according to claim 1, the combination as set forthincluding a metal frame extending about the periphery of said partition,and wherein said elongated members are of rigid construction and eachsecured at opposite ends thereof to said frame.

References Cited by the Examiner UNITED STATES PATENTS 1,855,745 4/1932Keenan 122- 235 2,337,208 12/1943 Reintjes 122-235 2,869,518 1/1959Seidl et al. 122-478 3,062,197 11/1962 Fleischer 122510 3,181,508 4/1965Hennipman 122-356 KENNETH W. SPRAGUE, Primary Examiner.

1. IN VAPOR GENERATING AND SUPERHEATING APPARATUS, THE COMBINATION OF:WALL STRUCTURE DEFINING A SHELL HAVING UPPER AND LOWER COMPARTMENT ANDINCLUDING AN INTERNAL HORIZONTAL PARTITION BETWEEN SAID UPPER AND LOWERCOMPARTMENTS, SAID LOWER COMPARTMENT INCLUDING A FURNACE CHAMBER, APLURALITY OF SUPERHEATER HEADERS DISPOSED IN SAID UPPER COMPARTMENT, APLURALITY OF ROWS OF UPRIGHT TUBES, EACH EXTENDING THROUGH SAIDPARTITION INTO SAID UPPER COMPARTMENT AND CONNECTED TO AT LEAST ONE OFSAID HEADERS, SAID PARTITION INCLUDING: A PLURALITY OF HORIZONTALLYEXTENDING, FLUID-CONDUCTING TUBES ARRANGED CLOSELY SPACED IN A ROW ATTHE BOTTOM OF SAID PARTITION, A PLURALITY OF HORIZONTALLY EXTENDING,ELONGATED METAL MEMBERS JOINED TO ONE ANOTHER ALONG ADJACENTLONGITUDINAL EDGE PORTIONS TO FORM A FLUIDTIGHT TOP SURFACE OF SAIDPARTITION, WITH AT LEAST SOME OF THE ELONGATED MEMBERS HAVING ALONGITUDINAL SERIES OF HOLES SLIDABLY RECEIVING REPSECTIVE UPRIGHT TUBESTO HOLD SAID TUBES IN ROW AND AGAINST TRANSVERSE MOVEMENT, AND A BODY OFINSULATING REFRACTORY MATERIAL BETWEEN SAID HORIZONTAL TUBES AND THE TOPOF SAID PARTITION INCLUDING A LAYER OF CASTABLE REFRACTORY MATERIALPOURED IN PLACE SO AS TO REST UPON SAID HORIZONTAL TUBES AND BESUPPORTED THEREBY.